Ought to be fine with your HTC or Ipad charger. I unplug my Samsung tablet from it's charger and plug in there. By definition, the output has to be at least 500 mA for USB2, and the MVP only takes around 420.
The provided cable has several connectors on it, so it will work to charge some
devices from the MVP, as well as charging the MVP.
I also picked up a retractable micro usb cable, and frequently just plug that into my Samsung charger or multi-port wall wart (search Amazon, just be sure to get one that provides the full 500 ma to
each port! Don't pay more than $20.) if I'm charging more than one
device at a time.